The invention relates to a drive device for an electric bicycle, in particular for a Pedelec which is operated in a hybrid fashion by electric motor or by muscle force.
An electric bicycle is to be understood either as an electrical bicycle (E-bike or eBike), which is a bicycle with an additional or integrated electric motor, wherein the supply thereof with electrical energy is effected by an accumulator, or a Pedelec in case of which an electric motor does not provide any power without turning the pedals with the exception of an application as pushing or start-up aid up to a velocity of 6 km/h. In order to switch on or the control of the electric motor of a Pedelec                the power or the torsional moment can be measured via the signal of a power sensor at the pedals, the pedal crank, the chain or at the wheel,        the pedal velocity can be measured via the signal of a rotation number sensor,        the velocity of the vehicle can be measured on the wheel, in particular in order to switch off the electric motor at a velocity of 25 km/h,        the acceleration can be measured,and the measurement can be further processed mechanically or electronically in order to switch on or switch off the electric motor or to regulate continuously by means of a control function.        
The power fed into the electric motor is calculated based on the sensor data depending on a selected supporting degree from the motor control such that the electric motor adds automatically a specific percentage of the power provided by the driver. The supporting degree or percentage of the power added by the electric motor can be adjusted in multiple stages or can be firmly fixed by the manufacturer or a mechanic.
A drive device with an electric drive for a bicycle operated by muscle force is known from EP 2 216 242 A1, which comprises an installation sleeve, which is anchored in a bush of a frame part of the bicycle, a crank shaft, wherein at the end thereof cranks for muscle power actuation connected to pedals are provided, and a drive sleeve arranged coaxially to the crank shaft, which is mounted in the installation sleeve. The drive sleeve contains an adapting disc at one end, which is connected to a chain wheel. A pedal crank free-wheel as clutch depending on the rotation direction is arranged between the crank shaft and the drive sleeve, while the drive sleeve is connected to the rotor of an electric motor via a drive free-wheel and a gear. Torsional moment and rotation number sensors are provided for detecting the torsional moment and the rotation number of the crank shaft, which deliver signals to an electric control, which determines the power applied by the driver and controls the electric motor for supporting the driver.